A very large part of all traded goods in the world is transported over sea by container ships. The ever increasing amount of international trade results in higher demands of container terminals all over the world to process (import/store/export) more goods with an increased speed. The demand on increased throughput capacity of container terminals often implies making very expensive investments. Such investments could be in terms of larger blocks (if even possible) and more cranes, other transport vehicles and complex and expensive computer systems. The reason for this is to be able to serve more import/export activities, and the resulting intermediate storage without incurring longer, costly delays in either end. For many small to medium sized terminals such investments might be too large to bear. Improved planning and handling of the storage blocks in a terminal has a great potential to increase the overall terminal throughput since this part is often a bottleneck in the whole inter modal transport system.
A system to optimize the block handling operations could increase the capacity of terminals too small to afford the high investment costs of large facility improvements. In addition, larger terminals could of course also benefit from a system that increases their capacity and effectiveness.
The traditional solution is to have a logistics system for the entire port handling all blocks and loading/unloading of the ships. The port logistics system determines in which block a certain container should be stored and communicates this information to a crane control system that inserts the container in the appropriate block. The export of a specific container is ordered by the port logistics system and the information is communicated to the crane control system for the appropriate block and the specific container is removed from the block where it has been stored.
In the published US application US2006/0182527, by Ranstrom et al., a system has been disclosed in a port logistics system which controls the movements of containers within each block by assigning orders to the cranes to perform a specific task.
A drawback of the prior art system is that only the port logistics system has an overall picture of each block and the crane available for moving the containers within each block performs the assigned orders whenever the port logistics system detects a container to move to a more favorable position. A small port without an expensive port logistics system having only one or a few container blocks will lack the possibility to use the unused capacity of the crane to optimize the position of each container within the block.
Another drawback is that each crane performs the assigned orders in the order they are assigned to the crane, which may introduce extensive crane motion before the next assigned order may be expedited.
Thus, there is a need to provide an improved system for optimizing the position of each container in a block without the presence of a port logistics system.